public void CancelAllAsync()
{
if (!_supportsCancellation)
{
throw new InvalidOperationException("This instance of the QueuedBackgroundWorker does not support cancellation.");
}
lock (_collectionsLock)
{
_cancelAllPending = true;
foreach (object key in _userStateToOperationMap.Keys)
{
OperationInfo opInfo = _userStateToOperationMap[key] as OperationInfo;
if (opInfo != null)
{
opInfo.OperationRequest.Cancel();
}
}
}
}
public void RunWorkerAsync(object userState)
{
if (userState == null)
{
throw new ArgumentNullException("userState cannot be null.");
}
int prevCount;
OperationRequest opRequest = new OperationRequest(userState, OperationHandler);
OperationInfo opInfo = new OperationInfo(opRequest);
lock (_collectionsLock)
{
if (_userStateToOperationMap.ContainsKey(userState))
{
throw new InvalidOperationException("The specified userKey has already been used to identify a pending operation. Each userState parameter must be unique.");
}
//Make a note of the current pending queue size. If it's zero at this point,
//we'll need to kick off an operation.
prevCount = _operationQueue.Count;
// Place the new work item on the queue & also in the userState-to-OperationInfo map.
//
_operationQueue.Enqueue(opInfo);
_userStateToOperationMap[userState] = opInfo;
}
if (prevCount == 0)
{
// We just queued up the first item - kick off the operation.
//
opRequest.OperationHandler.BeginInvoke(opInfo, OperationHandlerDone, opInfo);
}
}
private RunWorkerCompletedEventArgsWithUserState OperationHandler(OperationInfo opInfo)
{
object userState = opInfo.OperationRequest.UserState;
DoWorkEventArgs eventArgs = new DoWorkEventArgs(userState);
try
{
RaiseDoWorkEventFromAsyncContext(eventArgs);
if (eventArgs.Cancel)
{
opInfo.OperationRequest.Cancel(); // For the sake of completeness.
return(new RunWorkerCompletedEventArgsWithUserState(null, null, true, userState));
}
else
{
return(new RunWorkerCompletedEventArgsWithUserState(eventArgs.Result, null, false, userState));
}
}
catch (Exception err)
{
return(new RunWorkerCompletedEventArgsWithUserState(null, err, false, userState));
}
}
private void RaiseWorkCompletedEventFromAsyncContext(OperationInfo opInfo)
{
opInfo.OperationRequest.AsyncOperation.PostOperationCompleted(RaiseWorkCompletedEventFromClientContext, opInfo);
}
private void RaiseProgressChangedEventFromAsyncContext(int percentComplete, object userState, OperationInfo opInfo)
{
ProgressChangedEventArgs eventArgs = new ProgressChangedEventArgs(percentComplete, userState);
opInfo.OperationRequest.AsyncOperation.Post(RaiseProgressChangedEventFromClientContext, eventArgs);
}